①20210309094500③ Three times of written blood collection needle Pen-type blood collection needle is seldom used in clinical practice. The structure of a written blood sampling needle is a perforating needle with a sharp edge at both ends. The middle and lower part of the needle tube is fixed on the needle base. The front end of the blood sampling needle for the written test is called venous puncture needle, and the back end is called blood sampling needle. The surface of the blood sampling needle is provided with a blood blocking sleeve, and both ends of the needle tube are provided with a protective sleeve. In clinic, written examination and typically it blood collection needle, one-time blood vessels use together, the rotary solid walk in a bright blood needle detector outside in front of intravenous puncture needles insert the vacuum pick blood vessels with the backend cavity, the trailing edge of the needle to the blood through the blood resistance, wear into the vacuum tube stopper, blood is pumped into the blood vessels under the action of a negative pressure blood collection needle this duplication method can implement multiple blood sample collection